1. Field of the Invention
The present invention relates to an apparatus and method for forming a seal pattern of a flat panel display device, and more particularly, to an apparatus and method for forming a seal pattern of a flat panel display device that can improve productivity.
2. Discussion of the Related Art
Advances in information technology result in an increase in performance requirements for display devices in various shapes. Correspondingly, various flat panel display devices, such as liquid crystal display (LCD) devices, plasma display panels (PDPs), electro luminescent display (ELD) devices, vacuum fluorescent display (VFD) devices, and the like, have been recently researched, and some of them have already been applied to various apparatuses in practice.
Among these flat panel display devices, LCD devices are most widely used for a mobile image display device in place of CRT monitors due to their advantages including excellent image quality, lightweight, compactness and low power consumption. Specifically, LCD devices have been developed for monitors of TV sets, which can receive and display broadcasting signals, and monitors of desktop computers as well as mobile display devices such as notebook computers.
In this regard, although various technological developments have been accomplished to enable the LCD devices to act as a screen display device in various fields, the LCD devices still have some problems in operation such as the quality of images. In order to apply the LCD devices to various apparatuses as a general screen display device, it is necessary for the LCD devices to realize high quality images such as high definition, high brightness and large size, while maintaining such advantages as decreased weight, compactness and low power consumption.
Such an LCD device generally includes a liquid crystal display panel to display an image and a driving unit to apply a driving signal to the liquid crystal display panel, in which the liquid crystal display panel includes a first substrate, a second substrate, a liquid crystal layer formed between the first and second substrates assembled to each other with a space defined therebetween. The first substrate (TFT array substrate) is formed with a plurality of gate lines arranged at uniform intervals in one direction, a plurality of data lines arranged at uniform intervals in another direction substantially perpendicular to the gate lines, and a plurality of pixel electrodes, each forming a matrix of pixel regions defined by the data lines and the gate lines crossing each other. A thin film transistor is provided in each pixel region as a switching element to transmit a data signal from the data line to the respective pixel electrode in accordance with a gate signal from the gate line.
The second substrate (color filter substrate) is formed with a black matrix layer to shield light from a portion excluding a pixel region, a color filter layer of R, G and B to display color images and a common electrode to form a predetermined electric field in conjunction with the pixel electrode. In an in-plane switching mode LCD device, the common electrode is formed on the first substrate.
The first and second substrates are assembled by means of a seal pattern with the liquid crystal layer disposed in the space therebetween. Methods for forming a liquid crystal layer between the first and second substrates are divided into an injection method and a dropping method.
For the injection method, an injection hole formed on the liquid crystal display panel with the seal pattern is first immersed into a container filled with liquid crystal within a chamber set to a predetermined vacuum level. Then, the vacuum level of the chamber is changed so that the liquid crystal is injected into a space of the assembled panel through the injection hole due to a pressure difference between an interior of the liquid crystal display panel and an outside thereof. To complete forming a liquid crystal layer of the liquid crystal display panel, the injection hole is then sealed.
For the dropping method, after a seal pattern is formed around an outer periphery of an image display unit of one of the first and second substrates, liquid crystal is dropped to and dispersed on the substrate having the seal pattern formed thereon. Then, a pressure is applied between the first and second substrates to integrate the first and second substrates with the seal pattern and uniformly distribute the liquid crystal on the overall surface of the image display unit, thereby forming a liquid crystal layer of the liquid crystal display panel.
Generally, in the manufacturing of the liquid crystal display panel as described above, a plurality of liquid crystal display panels are simultaneously formed on a large-size mother substrate in order to improve productivity. Accordingly, it is necessary to separate each liquid crystal display panel from the large-size mother substrate by cutting and machining the mother substrate.
FIG. 1 is a schematic view illustrating an apparatus for forming a seal pattern on a substrate according to the related art.
Referring to FIG. 1, the apparatus for forming the seal pattern includes a mother substrate 20 having a plurality of unit display panels 10 formed thereon, a stage 30 movable in the forward, backward, right and left directions while supporting the mother substrate 20, and a pattern forming unit 50 to form a seal pattern 40 around an outer periphery of each unit display panel 10 on the mother substrate 20.
The stage 30 supports the mother substrate 20 loaded thereon from the outside, and can be moved in the forward, backward, right and left directions by a driving unit (not shown).
The mother substrate 20 may be one of first and second substrates. The mother substrate 20 is a large-size substrate and has a plurality of unit display panels 10 formed thereon. Each unit display panel 10 becomes a flat panel display device such as an LCD, PDP, ELD or VFD.
The pattern forming unit 50 includes a seal head 70 to form the seal pattern 40 around the outer periphery of each unit display panel 10 of the mother substrate 20 and a controller 60 to control the seal head 70. In response to a control signal from the controller 60, the seal head 70 forms the seal pattern 40 around the outer periphery of each unit display panel 10 in such a way as to apply a sealant to the mother substrate 20. The stage 30 is conveyed by the driving unit (not shown) to allow the seal pattern 40 to be formed around the outer periphery of each unit display panel 10.
A method for forming a seal pattern with the apparatus according to the related art will now be described.
First, the mother substrate 20 having the plurality of unit display panels 10 formed thereon is loaded on the stage 30.
After aligning the stage 30 and the seal head 70, the seal head 70 is controlled by means of the controller 60 to subsequently apply a sealant to an outer periphery of each unit display panel 10 on the mother substrate 20. The stage 30 is moved in the forward, backward, right and left directions such that the sealant is applied to the outer periphery of each unit display panel 10 from the seal head 70.
In the apparatus and method for forming the seal pattern according to the related art, the seal head 70 forms the seal pattern around the outer periphery of each unit display panel 10 formed on the mother substrate 20. However, when the size of the display panels 10 formed on the mother substrate 20 is changed in accordance with changes in design of the display panels 10, the apparatus and method for forming the seal pattern according to the related art may not efficiently cope with change of size, especially in light of the recent trend toward large-size display panels, which in turn requires an increase in size of the mother substrate. In other words, when the locations of the seal patterns formed on the mother substrate 20 are changed, it is necessary to reconstitute the pattern forming unit 50 including the reconstitution of the seal head 70.
Accordingly, the apparatus and method for forming the seal pattern according to the related art is disadvantageous in that it takes a long time to form seal patterns, thereby decreasing productivity.